خيارات البحث
النتائج 6061 - 6070 من 6,546
Mitigating biofouling with a vanillin coating on thin film composite reverse osmosis membranes النص الكامل
2020
Shin, Hyunseo | Park, Chansoo | Lee, Chang Kyu | Lee, Yong-Soo | Kim, Jong-Oh
Several methods, such as pretreatment, membrane surface modification, feed water chlorination, and chemical cleaning, have recently been applied to control biofouling on reverse osmosis (RO) membranes—with limited success. As an alternative, compounds that inhibit bacterial quorum sensing can be used to disrupt formation of bacterial colonies. In this study, anti-biofouling using vanillin, which is a natural substance among quorum sensing inhibitor compounds, was trialed, by modifying RO membrane surfaces with vanillin, at various concentrations. We then reviewed consequential changes to membrane surface characteristics and vanillin anti-biofouling properties. A long-term RO membrane simulator was used to analyze permeability, contact angle was measured for hydrophilicity evaluation, and membrane surface morphology was analyzed, through atomic force microscopy and scanning electron microscopy. A quorum quenching effect was confirmed by utilizing Petrifilm to count bacteria on the surface of a modified membrane. As a result, the permeability of the surface modified membranes was slightly decreased compared to the pristine membrane, but the hydrophilicity was increased, and the number of colonies decreased remarkably, the membrane modified with 0.5 M vanillin outperforming that modified with 0.25 M vanillin.
اظهر المزيد [+] اقل [-]Bioaerosol impact on crop health over India due to emerging fungal diseases (EFDs): an important missing link النص الكامل
2020
Yadav, Shweta | Gettu, Navin | Swain, Basudev | Kumari, Kiran | Ojha, Narendra | Gunthe, Sachin S.
Atmospheric bioaerosols, which contain a diverse group of various biological materials, also include pathogenic microorganisms such as viruses, bacteria, and fungal spores. The dispersal of various pathogens negatively impacts the human and ecosystem health. While the impact of pathogenic bacteria and viruses on human and ecosystem health is well documented, the impact of fungal spores on crop, however, is poorly characterized. An unprecedented increase in number of fungal and fungal-like diseases (emerging fungal diseases (EFDs)) in plants is threatening the food security and endangering the biodiversity. In present communication, we show an increasing trend in the fungal bioaerosol attacks on crops over India outstripping bacteria and viruses. We further argue about the complex interactions between the fungal species, and crop impact over India is unique and highly interconnected with the topography, meteorological variables, and season of the year. Under constantly warming scenario, the fungal attacks on plants are expected to rise and, in all likelihood, extend to the sensitive and fragile ecosystems like the Himalayan region and the Western Ghats. An increasing trend in EFDs calls for immediate coordinated efforts towards understanding the type and diversity of pathogenic fungal bioaerosols. There is, however, a lack over Indian region about biogeography of pathogenic fungi. The detailed biogeography would help in improving public and political awareness to formulate the effective policy decisions. Any further disregard and delay in recognizing the importance of EFDs to crop and sensitive ecosystems can have severe societal and ecological repercussions over Indian region.
اظهر المزيد [+] اقل [-]Root morphological response of six peanut cultivars to chromium (VI) toxicity النص الكامل
2020
Zong, Haiying | Liu, Jun | Wang, Fangli | Song, Ningning
We investigated the hypothesis that root morphology plays a crucial role in the variation in chromium (Cr) accumulation among peanut (Arachis hypogaea L.) cultivars, using the relationship between Cr accumulation and morphological characteristics of six peanut cultivars determined under 0, 10, 25, 75, and 100 μmol L⁻¹ Cr(VI) via hydroponic experiment. Significant variations were observed in Cr accumulation and root morphological parameters among peanut cultivars at the five Cr levels. The Cr concentrations in plants exhibited 1.72-, 4.67-, 1.81-, and 2.91-fold variations within cultivars for 10, 25, 75, and 100 μmol L⁻¹ Cr treatments, respectively. Positive correlations were found for total Cr in plants with total root length (RL), root surface area (SA), and root volume (RV). Negative correlations were also observed between the percentages of Cr in shoots and specific root length. These results suggest that root system morphology may partly explain the variation in Cr accumulation among cultivars. Cultivars with greater RL, SA, and RV showed higher capability for Cr accumulation.
اظهر المزيد [+] اقل [-]Revisiting the pollution haven hypothesis in ASEAN-5 countries: new insights from panel data analysis النص الكامل
2020
Guzel, Arif Eser | Okumus, İlyas
Pollution haven hypothesis (PHH) has been investigated extensively in the existing literature due to global environmental issues such as global warming and climate change. However, there is still no consensus on whether this hypothesis is valid. Therefore, the aim of this study is to examine the validity of the PHH in ASEAN-5 countries (Indonesia, Malaysia, Philippines, Singapore, and Thailand) covering the period of 1981–2014. It is utilized the up-to-date panel data techniques taking cross-sectional dependence and slope heterogeneity into account to test the relationship. According to the results of CCEMG and AMG estimators, the validity of the PHH is confirmed in ASEAN-5 countries. The increase in foreign direct investments (FDI) increases environmental degradation in these countries. Our additional findings show that the environmental Kuznets curve (EKC) hypothesis (EKC) is also valid in these countries. There is an inverted U shape between economic growth and CO2 emissions. In addition, energy consumption exacerbates CO2 emissions.
اظهر المزيد [+] اقل [-]Production of a bioflocculant from Enterobacter sp. P3 using brewery wastewater as substrate and its application in fracturing flowback water treatment النص الكامل
2020
Ma, Lili | Liang, Jingjing | Liu, Yucheng | Zhang, Yirong | Ma, Pengchao | Pan, Zhicheng | Jiang, Wenju
A novel bioflocculant (BW-P3) was produced by a strain of Enterobacter sp. P3 using brewery wastewater as substrate and was further applied to remove the colored substance of fracturing flowback water. The optimum conditions for bioflocculant production were specified by the response surface methodology as COD of brewery wastewater 1487.77 mg/L, glucose 8.94 g/L and initial pH 7.09, under which a bioflocculant yield of 1.274 g/L could be reached. The BW-P3 consists of 79.12% polysaccharides and 15.63% protein. Results show that BW-P3 has a high molecular weight (921 kDa) and contains functional groups (hydroxyl, amino, carbonyl, and acylamino) that likely contribute to flocculation. When using the BW-P3 to flocculate fracturing flowback water, the optimal dosage was 1 g/L BW-P3 with addition of 100 mg/L polymeric aluminum chloride as coagulant aid, and treated under 50 °C at pH 7. Under the optimal condition, the removal rates of chroma and suspended solids (SS) of the fracturing flowback water could reach 85% and 52%, respectively.
اظهر المزيد [+] اقل [-]Levels and ecological and health risk assessment of PM2.5-bound heavy metals in the northern part of the Persian Gulf النص الكامل
2020
Faraji Ghasemi, Fatemeh | Dobaradaran, Sina | Saeedi, Reza | Nabipour, Iraj | Nazmara, Shahrokh | Ranjbar Vakil Abadi, Dariush | Arfaeinia, Hossein | Ramavandi, Bahman | Spitz, Jörg | Mohammadi, Mohammad Javad | Keshtkar, Mozhgan
Bushehr, a port along the northern part of the Persian Gulf, has repeatedly encountered dust storms in recent years but there is not been a comprehensive study on the PM₂.₅ contents in this region. The present study reports the characteristics and health risks of atmospheric PM₂.₅-bound heavy metals (HMs) in Bushehr from December 2016 to September 2017. A total of 46 samples were analyzed, and a high volume air sampler equipped with quartz fiber filters was used for sampling. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was also used for HMs analyses. Risk assessment and hazard index (HI) of these metals were computed by using USEPA’s exposure parameters. The results showed that the average 24-h mass concentration of PM₂.₅ ranged from 22.09 to 292.45 μg/m³. The results also indicated that 95.65 and 82.61% of the samples were higher than WHO and EPA guidelines for 24-h PM₂.₅. Also there was no statistically significant relationship between wind direction and PM₂.₅.The average concentration levels of seven measured metals (Cd, Co, Cr, Fe, Ni, Pb, and V) in the PM₂.₅ samples were in the range of 6.03 ng/m³ to 1335.94 ng/m³, and the order of their concentration was Fe > Ni > Pb > Cr > Cd > V > Co. Principal component analysis (PCA) showed that PM₂.₅-bound heavy metals were categorized in three groups. The ecological risk level of calculated metals was very significant, and the major contribution of the ecological risk was related to Cd. The highest HQ in children and adults was related to Cr, and overall HI in children was higher than adults. Also the RI values of Cr in both groups of children and adults were indicated high risk of developing cancer in human.
اظهر المزيد [+] اقل [-]Structure, diversity and ecological function of shrub species in an urban setup of Sarguja, Chhattisgarh, India النص الكامل
2020
K̲h̲ān, Nāhīd | Jhariya, Manoj Kumar | Yadav, Dhiraj Kumar | Banerjee, Arnab
The vegetation plays important role in urban environment and associated ecology. Urban vegetation experienced various changes due to biotic and natural interference which alter the vegetation structure, function and ecology. The present study deals with the assessment of shrub species structure, diversity, biomass, volume, C storage and CO₂ mitigation potential in an urban setup. Total four sites were selected, viz., east, west, north and south directions of Ambikapur City. A sum of eight shrub species representing seven families was recorded in Ambikapur City area. The highest representatives were recorded towards east direction (seven species with six families) and lowest towards south direction (five species with five families). The total density of shrubs ranged between 230 and 570 individual ha⁻ ¹ being highest at east direction and least at south direction. The higher diversity was found at east direction. The shrub biomass was ranged between 0.999 and 2.603 t/ha being highest at north direction and lowest at east direction. The shrub volume, C storage and CO₂ mitigation values reflected similar trend as in case of shrub biomass. The shrub volume, C stock and CO₂ mitigation values were ranged from 0.141 to 0.250 m³/ha, 0.437 to1.132 t/ha and 1.597 to 4.156 t/ha, respectively, among the various sites. The species like Cestrum nocturnum and Nerium oleander are found to be potential in terms of various ecological services such as biomass, C storage and CO₂ mitigation in different sites. However, Lantana camara was also found to be potential species under urban setup which can be utilized for its various ecological functions. Further, it was found that the contribution of the non-native species was higher over native species in terms of stand density, basal area, biomass, C stock, volume and CO₂ mitigation potential among different study sites.
اظهر المزيد [+] اقل [-]Adsorptive removal of lanthanum based on hydrothermally synthesized iron oxide-titanium oxide nanoparticles النص الكامل
2020
Danish, Ekram Y. | Marwani, Hadi M. | Almoslehi, Kholoud F. | Bakhsh, Esraa M.
Iron oxide-titanium oxide (Fe₂O₃-TiO₂) nanoparticles were developed as an effective adsorbent in order to extract and remove lanthanum ions selectively from aqueous media. Fe₂O₃-TiO₂ nanoparticles were prepared by simple hydrothermal method and structurally characterized using FESEM, EDS, XRD, FTIR, and BET techniques. The analytical potential of Fe₂O₃-TiO₂ nanoparticles was interpreted by applying the kinetic and isotherm models. The maximum static uptake capacity was 89.63 mgg⁻ ¹ at pH 7. Adsorption isotherm data evinced that a monolayer adsorption occurred on a homogeneous adsorbent surface which is compatible with Langmuir isotherm model. Data acquired from kinetic models study proved that La (III) adsorption onto Fe₂O₃-TiO₂ nanoparticles followed a pseudo-second-order kinetic equation. Thermodynamic study exhibited that a spontaneous process is favorable for adsorption mechanism of La (III) on Fe₂O₃-TiO₂ nanoparticles. Moreover, the existence of different coexisting ions did not influence the extraction of La (III). Finally, the recommended methodology was applied on several environmental samples.
اظهر المزيد [+] اقل [-]Multi-walled carbon nanotubes induce oxidative stress, apoptosis, and dysfunction in isolated rat heart mitochondria: protective effect of naringin النص الكامل
2020
Salehcheh, Maryam | Alboghobeish, Soheila | Dehghani, Mohammad Amin | Zeidooni, Leila
Multi-walled carbon nanotubes (MWCNTs) are material with exclusive features that can be applied in different fields including industrial and medicine. It has been determined that the accumulation of MWCNTs in the organs is along with genotoxic and cytotoxic injuries. Previous studies have shown mitochondrial dysfunction in MWCNTs exposure with cell lines, but their exact mechanisms with isolated mitochondria have remained unclear. The present study evaluated toxicity induced by MWCNTs in isolated rat heart mitochondria and protective effect of naringin. Our results showed that MWCNTs toxicity caused the prevention of heart mitochondrial complex II activity. Treatment of isolated heart mitochondria with MWCNTs led to an increase in mitochondrial reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) collapse, and mitochondrial malondialdehyde (MDA) and a decrease in mitochondrial glutathione (GSH) level and mitochondrial catalase (CAT) activity. Pretreatment of isolated heart mitochondria with naringin decreased mitochondrial oxidative damage through decreasing lipid peroxidation, returned mitochondrial complex II changes, decreasing MMP collapse and ROS production, and restoration of GSH level and CAT activity. Our findings indicated that MWCNTs had toxic effects on isolated heart mitochondria by inducing oxidative stress and possibly apoptosis pathway. The protection effects of naringin may be accompanied by mitochondrial conservation by its antioxidant property or due to its free radical scavenging. Our findings indicated that naringin had a possible role in preventing the mitochondria complaints in the heart.
اظهر المزيد [+] اقل [-]Using graphene quantum dots for treating radioactive liquid waste النص الكامل
2020
de Menezes, Frederico Duarte | Alencar, Luciana Magalhães Rebelo | dos Santos, Clenilton Costa | da Silva, Maria Isabel Barbosa | Santos-Oliveira, Ralph
The use of smart materials, especially the carbon-based nanomaterials, is increasing each day. Among the several carbon-based nanomaterials, graphene quantum dots are one of the most impressive ones, not only by its quantum behavior but due to the adsorption quality conferred by electrostatic interactions from the negatively charged groups as the huge surface area (2.630 m2/g). In this study, we developed and tested graphene quantum dots (GQDs) as smart nano-adsorbents of uranium (²³⁸U) from the radioactive industry waste. The GQDs were developed in a size range of 160–220 nm using a totally green route. The results showed that the GQDs were capable to adsorb almost 40% of the uranium (²³⁸U) in alamine 3366 solution. Also, the results demonstrated that using GQDs treatment-like smart nanomaterials for radioactive waste in a volume reduction of almost 90% is achieved, helping the storage process as the final disposal of this material. We may conclude that GQDs may represent a smart device for the treatment of radioactive waste as an alternative of absorbent in the radioactive industry.
اظهر المزيد [+] اقل [-]